Volvox and Associated Algae from Kimberley. 519 



no. 



D. Portion of mixed colony with young daughter colony in which the difference 



between gonidia and somatic cells is already well defined, a young oospore, 

 two somatic cells, and several scattered spermatozoids (623). 



E. Volvox africanus, recently inverted daughter colony showing the four equatorial 



gonidia projecting from the periphery (657). 



A, C x 545. B x 45. D, E x 330. 



PLATE XXXI. 

 Volvox africanus G. S. West. 



A. Group of colonies showing general appearance ; embryos in all stages of 



development from undivided gonidia to mature daughter colonies ready to 

 escape and containing embryos already in advanced stages of division (649). 



B, C. Colonies with maturing embryos, C stained with methylene blue to show 



the membranes. The gap left by the escape of an equatorial embryo shows 

 at each side ; the three remaining daughters have developed from the more 

 posterior gonidia, pushing up the inner membrane of the parent colony as 

 they increased in size. This colony, unstained, is on the right in the group 

 above (650, 652). 



D. Younger colony with four large equatorial and a very much younger pair of 

 posterior embryos (651). 



A x 25. B to D x 70. 



PLATE XXXII. 

 Voh-ox (ifricnnus. Inversion of embryo. 



A, B. Large colony with two pairs of maturing embryos (equatorial), one pair 

 recently inverted, in one of which the gonidia have sunk into position, while 

 in the other they are still projecting (see Plate XXX, E), and one pair in 

 the process of inversion. A, top, and B, median focus (654, 653). 



C, D. Inverting daughters from the above, side view. In D the folded-back lip 

 is straightening out, forming a wide fringe round the embryo (656, 655). 



E. Phialoporic view of D ; four large gonidia lie in the depression just outside 

 the four sides of the pore (659). 



A, B x 70. C, D x 330. E x 520. 



PLATE XXXIII. 

 Volvox africanus. Inversion of the embryo, continued. 



A, B. Early " hat " stage of inversion, edge of phialopore folding back doubled 

 up ; in A a gonidium shows at the bend on the right. B, the same colony 

 with slightly different focus, showing the pointing of the outer ends of the 

 cells in the posterior region (666, 670). 



C. Phialoporic view of the same colony (668). 



